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Aviation History
1957
1957 - 0105.PDF
25 January 1957 105 CL-28 Some Notep on the Largest Aeroplane Yet Built in Canada ON December 28 the Canadair Division of the GeneralDynamics Corporation completed the erection of the firstCL-28 long-range maritime patrol aircraft for the Royal Canadian Air Force. The impressive machine was towed fromthe end of the final assembly line at Canadair's Plant 1 at Montreal and is now in the recently extended pre-flight hangar. After beingfully equipped, having a detailed weight check and completing vibration testing the machine is to fly early in the spring. As we have often reported, the CL-28 is based on the BristolBritannia. It is, however, an extensively redesigned aeroplane and many of its features are of uncommon technical interest. Since the war ended in 1945 the defence of Canada has posedmany weighty problems, which have been accentuated by Canada's generosity in supplying a degree of fighting strength to NATOquite out of proportion to her population. One of the most pressing difficulties has been to ensure that no possible aggressorcould disrupt the sea routes leading from the Dominion's Atlantic and Pacific coasts. Patrolling these routes has been a major taskof the R.C.A.F. Maritime Air Command, and valiantly have the crews of this command ranged far and wide over vast expansesof friendless and freezing ocean in their Lancaster MR.lOs. Nevertheless, by 1953 the beloved Lanes were showing theirage. It was increasingly apparent that something better would have to be provided—something in which a crew could fly for25 or 30 hours without becoming unduly fatigued, and which could also carry the most modern search and attack equipment. It wasappreciated from the outset that the ideal aircraft would be excep- tionally large; piston engines would be mandatory to confer greatendurance at low levels, a big, high-lift wing would be essential to get the weight of fuel and military gear off the ground and thefuselage would need to be capacious and comfortable. Development of such an aeroplane is an expensive business andit was logical that the Canadian Department of Defence Production should minimize cost and time by choosing as a basis an existing,fully developed transport aircraft. There were several possibilities. Finally, well into 1953, the choice hardened on the Bristol Britannia.It was realized that conversion of such a machine would be a tremendous undertaking, but the Britannia had unmatched attrac-tions in its combination of a modern and lightweight structure, large internal tankage, a simple and effective flight-control systemand many other advantages which bring no small credit to the original Bristol design team. By the end of 1953 the die was cast (figuratively, if not yetliterally) and the following April Canadair were given respon- sibility for the project—as the CL-28—with an initial order forthirteen aircraft. Since that time Canadair's work has been out- standingly well planned, as befits a division of one of the world'slargest industrial organizations. The Montreal plants employ about 9,000 and occupy some 2.6m square feet of floor area.Plant 2, on the far side of the airfield, is gradually coming to the end of the long and prolific lines of F-86s and T-33s, and thecontract for the giant ocean-patroller has been Canadair's biggest stake in the future since the small jets began to "taper off." It is, in fact, not surprising that the company have kept mostof the CL-28 work to themselves. Apart from the "systems," powerplants, undercarriage and military equipment, Canadairhave designed and are manufacturing virtually the whole aero- plane. This is a unique state of affairs in the modern Canadianscene, where most projects are shared by several firms. Like Britain, the Dominion is suffering from a progressive "stretch-out" in military procurement, and Canadair are adopting a long- term viewpoint with the CL-28. In fact, as the orders haveprogressively increased so have the company stretched their pro- gramme to ensure that the production line will not suddenlyrun out. Bristol Aircraft and Canadair have co-operated closely on theCL-28 project since its inception. Early in 1954 a flood of Britannia drawings, which eventually numbered thousands, startedto flow from Filton to Montreal, and Canadair's D.O. staff began to appreciate the magnitude of the task facing them. After study-ing the British turboprop airliner in detail—to see, as one Canadian put it "what sort of an animal they had chosen to live with"—months were spent in Americanising the design (or perhaps it would be more precise to say "Canadianising"). Every sheet-gauge, every rivet and every screw-thread had tobe converted to its nearest safe transatlantic equivalent. Material specifications had to be found to correspond to those employed Roll-out on December 28; note the fin-slot cut in the hangar roof. in the British aeroplane, and machining and other operations hadto be programmed in detail—including a host of procedures quite new to Canadian aviation. By no means least, sub-contractorsand material suppliers had to be found, and their deliveries geared to the final production schedule. No alterations were countenanced without a really good reason,and substantial areas of the CL-28 are—except for the afore- mentioned naturalization—identical with those of the Britannia.In particular, the wing, flying controls and tail are essentially unchanged. The fuselage, however, is entirely different. To begin with it is unpressurized. Apart from the task of radarpicket, or high-altitude early warner, none of the missions of the CL-28 requires high-altitude ability; in fact, the reverse is gener-ally the case. Deletion of the pressurization has allowed appreci- able weight-savings, and the more one studies the CL-28 themore it becomes apparent that Canadair have gone all out to save inbuilt weight. Quite considerable effort has been expended inorder to prune off an ounce here and an ounce there, and, as will presently be described, certain design changes have lopped offhundreds of pounds. Nevertheless, Bristol's original airframe design is so efficientthat the CL-28 parallels it closely. Changes introduced as a result of deleting the pressurization are minor, although simplificationand a reduction in the weight of soundproofing has been made possible by the great reduction in fuselage window area. A majorchange, however, was required in order to carry the necessary operational equipment and weapons. There are two weapons bays, separated by the wing torsion-box,which passes straight through the fuselage. Major loads are carried past the bay cut-outs by boundary longerons. Each bayhas conventional outward-opening doors actuated hydraulically by jacks designed and produced by the Fairey Aviation Companyof Canada. No details of the offensive load may be published, but it is certain to include every available type of sonobuoy,mine, depth-charge, A/S. bomb, homing torpedo, air-to-surface missile (such as Petrel) and similar maritime devices, as well asnew weapons, now under development, which promise to revolu- tionize A.S.W. techniques. Possibly no other aeroplane is quite the equal of the CL-28 inthe matter of electronics. No fewer than 21 distinct radio or radar installations are standard, the most prominent being the search CANADAIR CL-28 Four Wright R-3350-34W Span 142ft 2Jin Length 122ft 1±in Height ... ... ... 36ft 8in Gross weight ... ... 148,000 1b
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